Until recently, telephone signaling systems have been provided almost exclusively on a per trunk in-band basis. That is, supervisory and called address signals have been transmitted over voice facilities in the process of establishing call connections. The CCIS system was recently introduced into service for the purpose of improving the signaling capacity and flexibility for the establishment of call connections from the voice facilities of the telephone network.
The CCIS system is a data communications network interconnecting telephone offices. Telephone offices that interface with the CCIS system are said to have CCIS capability. These offices have access to data links which are routed directly or indirectly through signal transfer points (STPs), to other offices having CCIS capability. The data links may also provide access from telephone offices to centralized data bases at which may be stored subscriber data for providing such services as enhanced Inward-Wide-Area-Telephone-Service (INWATS), now called "800 service."
The CCIS system now in operation employs a signaling arrangement in which all data messages are dependent on the existence of a particular voice facility. That is, each signaling data message now transmitted in the CCIS system contains an identification of a voice trunk selected for a call with which the data message is associated. The voice trunk identification provides the address of the destination (switching office) of the data message. Data messages are transmitted from destination to destination as a call is progressively established. In the near future a new form of signaling, referred to as direct signaling, will be introduced. Direct signaling messages may be sent directly to a final destination and do not have to be associated with a telephone call or with a voice trunk. These messages might contain, for example, network management information.
Direct signaling will allow the introduction of a host of new calling services to telephone customers. Many of these new services may be described as customized and may depend upon identifying the calling entity (party or station) or some other call identifying characteristic which entitles the call to some type of treatment different from ordinary calls. U.S. patent application Ser. No. 113,384, filed by D. Sheinbein on Jan. 18, 1980, describes in detail how some of these customized calls might be provided. Illustrative examples of the types of customized services that are planned include selective call acceptance, selective call waiting, selective automatic callback, priority ringing, etc. In selective call acceptance, for example, a subscriber prespecifies individuals or stations from which calls may be accepted. Calls from other individuals or stations are denied. Similarly, the other selective services mentioned above are provided on the basis of prespecified calling entities.
Up to the present time, it has been considered impossible to process these types of customized calls without end-to-end CCIS signaling. That is, it has been believed that all offices involved in the routing of such a call must have CCIS capability. The Sheinbein disclosure, for example, assumes that all offices in a call connection have access to the CCIS system. The reason for this is the need of identification at the terminating office to verify the entitlement of the call to the customized service. For example, in order to apply priority ringing to a subscriber's station who leases this service, a terminating office must verify that an incoming call is from an entity the subscriber has authorized for the priority ringing. In general, the method that has been contemplated for providing this information to the terminating office is to transmit CCIS data messages between each of the offices involved in the call. The messages would identify the calling entity and the interoffice trunk on which the call is being routed. In this manner, the terminating office would eventually receive a CCIS data message identifying the trunk on which a call is arriving and the calling entity associated therewith. The terminating office would then communicate with a data processing facility, for example, to determine if the called party subscribes to some type of customized service and if so, if the calling entity is authorized for the service.
In the event that a toll office, for example, used in establishing a call does not have CCIS capability, there is no way in the above-described method for that office to notify the succeeding office of what outgoing trunk is selected for the call. Even if the succeeding office has CCIS capability and is given a call identification by a data message from a prior office, there is no way for the succeeding office to associate the identity with a particular call arriving on a voice trunk. The result is that there is no way to identify the calling entity on a call arriving at the terminating office and, therefore, no way for the terminating office to verify the entitlement of the call to custom calling service.
It is expected that CCIS custom calling services will begin to be offered to the public in the near future. Under current thinking, however, only limited service can be offered until CCIS capability is universally available in the telephone network. This universal capability probably will not be achieved for many years. The lack of universal CCIS capability is therefore a serious detriment to the rapid introduction and acceptance of many new services.